It has long been the practice to enhance physical security at various installations by providing barriers constructed of barbed entanglement devices. These barriers usually take the form of helical coils of barbed materials which are placed atop walls and fences or arranged in stacked arrays between walls or fences. The oldest, and most common, form of barbed barrier is that made from barbed wire. Characteristically, barbed wire is only barely self-supporting and therefore can be crushed from a coil form with very little effort. Such barriers usually can be breached with very simple aids such as a heavy cloth or a board. Moreover, the rather flimsy appearance of the barbed wire and the fairly short, non-lethal, barbs thereon, often fail to discourage a person from attempting to breach the barrier. It has thus been recognized that for secure installations more rugged and more intimidating barriers are required. This has led to the development of barbed tape barriers.
There are two types of barbed tape in common use today. The first of these usually is referred to as "Barbed Tape Concertina" and is formed by clinching a strip of barbs over a high tensile, spring steel wire which is preformed to the desired helical configuration. This type of tape is disclosed in U.S. Pat. No. 2,908,484 granted Oct. 13, 1959 to S. Uhl for "BARBED WIRE SPIRAL" and U.S. Pat. No. 3,916,958 granted Nov. 4, 1975 to S. Uhl for "PROCESS AND APPARATUS FOR PRODUCING A BARBED SPIRAL". One disadvantage to this type of barbed tape is its cost, which is relatively high because of the requirement that spring quality steel be used for the supporting wire core of the tape. This tape is also deficient in its performance because the barrier coils are relatively weak in vertical compression. Even though it is the usual practice to clip together adjoining coils at spaced intervals to impart structural integrity to the barrier, simple breaching aids usually are sufficient to subvert the purpose of the barrier. Lastly, the short barbs usually provided on this type of tape and the "skinny" appearance of the tape render the tape only slightly more intimidating than ordinary barbed wire. Thus this tape fails to discourage attempts to breach it.
The other form of barbed tape in common use today is that known generally by its military designation of "General Purpose Barbed Tape Obstacle". This barrier consists of a unitary flat metal strip which is bent edge wise in the form of a helix and has portions cut away so that elongated barbs are provided at spaced intervals along the two edges of the strip. In some of these barriers, the strip is formed with a continuous uniform arcuate curvature as disclosed in U.S. Pat. No. 3,463,455 granted Aug. 26, 1969 to P. T. Meckel for "HELICAL BARBED TAPE UNIT". Other barriers of this type are formed by edge bending the strip into identically angularly displaced adjoining linear segments to form the helix. Such a tape is disclosed in U.S. Pat. No. 4,040,603 granted Aug. 9, 1977 to M. R. Mainiero for "BARBED METAL TAPE". The method for manufacturing this tape is disclosed in U.S. Pat. No. Re. 30,814 reissued Dec. 8, 1981 to M. R. Mainiero for "APPARATUS AND METHOD FOR FORMING BARBED TAPE". The Meckel patent and the Mainiero patents disclose techniques for providing shallow reinforcing channels or grooves throughout the linear extent of the tape strip, presumably for the purpose of rigidifying the resulting barrier. Norwithstanding such reinforcement, barriers formed in the manner taught by Meckel and Mainiero are required to be fabricated from either expensive, spring quality, austenitic stainless steel material or of lower quality steel in a thicker strip in order to possess sufficient strength to resist collapsing forces from breach attempts. Furthermore, in order to control bending of the strip of metal stock used to manufacture the Mainiero tape, it is usually necessary to punch holes in the tape at the bend locations and such holes further weaken the tape in edgewise bending.
The prior art also includes other barbed tape structures which have met with little or no commercial success. One such barbed tape is disclosed in U.S. Pat. No. 3,455,539 granted July 15, 1969, to J. G. Loofbourrow for "BARBED STRIP", which is required to be made of spring steel. U.S. Pat. No. 3,763,529 granted Oct. 9, 1973 to D. D. Musgrave for "METHOD OF FABRICATING BARBED TAPE" suggests reinforcing a barbed tape with wire which is secured to the tape either by welding or by having spaced segments of the tape bent around the wire. Both of these techniques appear to be costly and impractical.